Retinal disorders, including age-related macular degeneration, are leading causes of vision loss worldwide. New treatments, such as gene therapies and stem cell regeneration, require therapeutics to be introduced to the subretinal space due to poor diffusion to the active component of the retina. Subretinal injections are a difficult and risky surgical procedure and have been suggested as a candidate for robot-assisted surgery. We propose a different actuation paradigm to existing robotic approaches using remote magnetic navigation to control a flexible microcannula. A flexible cannula allows for high dexterity and considerable safety advantages over rigid tools, while maintaining the benefits of micrometer precision, hand tremor removal, and telemanipulation. The position of the cannula is tracked in realtime using near-infrared tip illumination, allowing for semiautomatic placement of the cannula and an intuitive user interface. Using this tool, we successfully performed several subretinal injections in ex-vivo porcine eyes under both microscope and optical coherence tomography visualization.

Compliant mechanisms gain motion through the elastic deformation of the monolithic flexible elements. The geometric design freedom of metallic additive manufacturing enables the fabrication of complex and three dimensional (3D) compliant elements within mechanisms previously too complicated to produce. However, the design of metallic additive manufactured mechanisms faces various challenges of manufacturing restrictions, such as avoiding critical overhanging geometries and minimizing the amount of support structure, which has been reported in a few cases. This paper presents a synthesis approach for translational compliant elements, involving building blocks based on leaf-type springs and covering building orientations between 0° and 90°. In particular, this range is approached by the synthesis of self-supported 3D building blocks with orientations of 0°, 45°, and 90°. The compliant elements are built based on linear and circular plane curves and compared numerically according to their mechanical performance to create preferable building blocks. The applicability of the presented procedure and the manufacturability of the compliant mechanisms are proven by printing individual 3D building blocks and their serial aggregation with laser based powder bed fusion. Consequently, several prototypes are demonstrated, including a bistable switch mechanism and a large displaceable rotational spring joint. In addition, a small-scale highly maneuverable segment of a surgical instrument with a grasping mechanism at the distal end is proposed.

No abstract

No abstract